The present invention relates to a wing box and a method of manufacturing a wing box. In particular, the invention relates to an aircraft wing box, a method of manufacture thereof, a method of designing a wing box, and a rib structure for use in a wing box.
Aircraft wing boxes are typically manufactured by forming a sub-structure by assembling non-formable components (for example including ribs and/or spars) and then mounting pre-formed wing covers on the sub-structure so formed. However, build-up of tolerances between the non-formable components makes it difficult to obtain an accurate connection of the wing cover to the sub-structure and difficult to achieve the desired aerodynamic profile. Thus, the build-up of tolerances may result in the mismatching/misfitting of the surfaces of the wing covers and the corresponding surfaces of the substructure at which the wing covers are joined thereto. Such problems have been solved by means of removing or adding material as appropriate by means of “fettling” or using “shims”, respectively. However, whilst such measures may allow the components to be flush before fastening, the addition or removal of material may affect the aerodynamic profile such that the profile is different from the desired profile.
Also fastening covers onto the substructure using fasteners requires the covers to have a certain thickness in the region of each fastener in order for the fastening to be sufficiently structurally strong. This increased thickness increases the mass of the covers. The mass of the wing covers is typically significantly greater than the mass of the ribs in the wing. It is desirable to reduce the mass of the aircraft, whilst not otherwise reducing performance or structural properties of the aircraft.
It is typical for certain in-wing systems, such as actuators, fuel systems and the like, to be integrated into the structure after at least some of the wing covers have been mounted onto the sub-structure. This complicates assembly of the wing box, but follows from the construction process outlined above, in which the covers are formed onto the substructure.
The present invention relates to an aircraft wing box, wherein the wing box comprises at least a pair of half ribs joined to form a rib extending from an upper wing skin to a lower wing skin. In certain embodiments of the invention, the aircraft wing box is assembled from two wing box halves, each wing box half comprising at least one half rib, and preferably a multiplicity of half ribs, each of which being joined to a half rib of the other wing box half. Utilising such a construction may have many benefits in accordance with embodiments of the present invention, as is explained in further detail below.